in this world, endmills are mass produced from human fingers grown on the backs of rats
rats grown fingers make general purpose and decent quality endmills direct-from-human grown fingers make endmills with unique properties, incentivizing the player to make this sacrifice
the endmill dispenser accepts two types of currency, one is chits, one is the players fingers. chits give mass produced endmills from rat-grown fingers. these raw materials are stored and locked in the machine, already severed from their discarded rat-hosts. the player-sacrificed fingers are accepted through the central iris.